Mode of producing wrought iron with increased tensile properties



Patented Sept. 25, 1928.

GEOBG GUDE GEDDA, F SURAHAMME R, SWEDEN.

MODE 0! PRODUCING WROUGH'I. IRON WITH INCREASEDTENSILE PROPERTIES.

1T0 Drawing. Application filedDecember 9, 1925, Serial No. 74,408, andin Sweden July 17, 1925.

Wrought iron processes heretofore practiced, such for example as thetriple melting- 5 and the puddlmg processes, have to a large extent beensuperseded b the ingot steel production, duepartly to t fact that thishas proven to be cheaper, and partly because it results in a producthaving its composition In so altered as to increase the tensileproperties thereof.

To substitute the ingot iron for the Wrought. iron has, however, beenimpossible for certain purposes. This is the case, when '5 the weldingcapacity and the fibrous structure, qualities which are characteristicof the wrought iron, are of a decisive importance. The production of awrought iron with its usual characteristic qualities, but

.20 with an improved tensile strength, has long been sought. For thispurpose an incomplete fining away of coal or manganese has beenproposedbut by this process the 'weld-' ing capacity isdisadvantageously afl'ected and the process is very unreliable, also. It

has also been proposed to use a pig-iron with a specially highpercentage of phosphorous;

in this case the whole phosphoric percentage is met with in the wroughtiron, which causes an improved tensile strength of the product, but alsoa greater brittleness and a greater. unreliability. Experiments havebeen made with cold rolling, but because of its unreliableness this modeis not practical,

at least when important construct-ion materials are concerned. In theseand other cases it has been possible to increase the elastic limit andto increase the maximum tensile strength, but the contraction and theimpact capacities have, on the other hand, always been decreased.

The problem ofincreasing the maximum tensile strength of the wroughtiron, and also increasing its elastic limit, without a simultaneous andconsiderable reduction .of' its welding capacity, as well as the impactand contraction capacities of the material, is

solved by the present invention.

I have discovered that this may be attained b an alloyin of the wroughtiron with nic el. It may e accomplished in vapact test 12-14 kg. cm./mm.the use of the rious ways. For example,as fining material I may use apig-iron, that previously has been a loyed with nickel, for instance bysuch means, that the nickel as pure metal or as an alloy has been put inthe charge used in the pig-iron production. The nickel may also be putin by such means, that the nickel, or a nickeliferous material, isplaced; in the finery or, it is possible by the use of nickeliferousiron in such a way to increase the quantity of nickel. Nickel being ametal with considerably less aflinity' for oxygen than the iron,practicall the whole quan tity of nickel used will orm a part of therefined iron. In the slag there will only be traces of nickel. Y a

A Lancashire bloom produced by the invention and containing 0,03% C,0,01% Si, 0,07% Mn, 0,006% s, 0,021% P and 3,57% Ni has, by analysis,1proved to have a maximum tensile strengti of 38,5 kg./mm; an elasticlimit of 30-31 kg./mm. a contraction of about-75% and an impact test asper Charpy of about 17 kg.cm./mm. Lancashire iron of the compositionmentioned above, without the nickel, has a maximum tensile strength ofabout 30 kg'n/mmf and an elastic limit of about 17 kg./mm. Thus thenickel has effected a material increase in the maximum tensile strengthand also in the elastic limit of the product. And as for usualLancashire iron the contraction seldom reaches more than 60-70% and theimnickel has also eflected a considerable increase in thesequantities ofthe product.

In the problem in question as in man other respects cobalt has proved tohavequa ities, which are similar to those of the nickel. Thence it ispossible to carry out the present invention with cobalt entirely orpartly substituted for the nickel.

For some purposes it may be convenient to alloy with-the wrought ironbesides the nickel or the cobalt also a small quantity of copper. To theother good 'qualities the use of copper adds an increased resistanceagainst rust.

-I claim as my invention:

1. The process of manufa'cturin wrought iron conslsting in heatingnickeli erous pig iron and puddling the same in aimannm to produce awrought iron to increase the usual tensile strength and elastic limitthereof Without decreasing its Welding and contracv t1on capacities.

2. The 'process of manufacturing Wrought iron consisting in adding apredetermined amount of nickel to ordinary pig iron and then heatingthe. mass and so puddling the same as to produce a Wrought ironofincreased tensile strength and elastic limit Without decreasing itsWelding and contraction capacities.

In Witness whereof, I have hereunto signed my name. 7

. sEoRG GUDE GEDDA.

